from the Post-Heliopause dept.
Ars Technica has word from the most distant human artifact.
The Voyager 2 spacecraft has been gone from Earth for more than 43 years, and it now lies 125 astronomical units from our planet. That is 125 times the distance between the Earth and Sun.
Understandably, this distance makes it rather difficult for NASA to communicate with its far-flung spacecraft—there is a time delay of more than 17 hours. However, with Voyager 2, there is another complication in talking to the spacecraft.
After flying by Jupiter, Saturn, and Uranus, Voyager 2 made its final planetary flyby in August 1989 past Neptune. Scientists were also interested in flying by Neptune's intriguing moon Triton, so they commanded Voyager 2 to do so on its way beyond Neptune, flying over the north pole of Triton. This trajectory carried it along a southward path relative to the plane of the Solar System, and it has kept on booking it south.
This has consequences for communicating with NASA's Deep Space Network on Earth, which consists of three large radio antenna facilities around the world, in California, Spain, and Australia. Typically, this geographical spread allows for all of NASA's spacecraft still active to have the capability to communicate with at least one of these facilities at all times.
But because Voyager 2 has dipped so far south of the plane of the Solar System, it can now only communicate by line of sight with the 70-meter-wide antenna in Canberra, Australia. Because this facility is about five decades old, it needed to undergo refurbishment and upgrade work beginning in March, and it had been offline since that time. This work is expected to conclude in February, so NASA has been unable to send signals to Voyager 2 since that time.
Must have been that left turn at Albuquerque.
In November 2018, after an epic, 41-year voyage, Voyager 2 finally crossed the boundary that marked the limit of the Sun's influence and entered interstellar space. But the little probe's mission isn't done yet - it's now sending home information about the space beyond the Solar System.
And it's revealing something surprising. As Voyager 2 moves farther and farther from the Sun, the density of space is increasing.
It's not the first time this density increase has been detected. Voyager 1, which entered interstellar space in 2012, detected a similar density gradient at a separate location.
Voyager 2's new data show that not only was Voyager 1's detection legit, but that the increase in density may be a large-scale feature of the very local interstellar medium (VLIM).
[...] One theory is that the interstellar magnetic field lines become stronger as they drape over the heliopause. This could generate an electromagnetic ion cyclotron instability that depletes the plasma from the draping region. Voyager 2 did detect a stronger magnetic field than expected when it crossed the heliopause.
Another theory is that material blown by the interstellar wind should slow as it reaches the heliopause, causing a sort of traffic jam. This has possibly been detected by outer Solar System probe New Horizons, which in 2018 picked up the faint ultraviolet glow resulting from a buildup of neutral hydrogen at the heliopause.
It's also possible that both explanations play a role. Future measurements taken by both Voyager probes as they continue their journey out into interstellar space could help figure it out. But that might be a long bet to take.
"It is not certain," the researchers wrote in their paper, "whether the Voyagers will be able to operate far enough to distinguish between these two classes of models."
Voyager 1 is still alive out there, barreling into the cosmos more than 15 billion miles away. However, a computer problem has kept the mission's loyal support team in Southern California from knowing much more about the status of one of NASA's longest-lived spacecraft.
The computer glitch cropped up on November 14, and it affected Voyager 1's ability to send back telemetry data, such as measurements from the spacecraft's science instruments or basic engineering information about how the probe was doing. [...] "It would be the biggest miracle if we get it back. We certainly haven't given up," said Suzanne Dodd, Voyager project manager at NASA's Jet Propulsion Laboratory, in an interview with Ars. "There are other things we can try. But this is, by far, the most serious since I've been project manager."
Dodd became the project manager for NASA's Voyager mission in 2010, overseeing a small cadre of engineers responsible for humanity's exploration into interstellar space. Voyager 1 is the most distant spacecraft ever, speeding away from the Sun at 38,000 mph (17 kilometers per second). [...] The latest problem with Voyager 1 lies in the probe's Flight Data Subsystem (FDS), one of three computers on the spacecraft working alongside a command-and-control central computer and another device overseeing attitude control and pointing. [...] In November, the data packages transmitted by Voyager 1 manifested a repeating pattern of ones and zeros as if it were stuck, according to NASA. Dodd said engineers at JPL have spent the better part of three months trying to diagnose the cause of the problem. She said the engineering team is "99.9 percent sure" the problem originated in the FDS, which appears to be having trouble "frame syncing" data. [...] "It's likely somewhere in the FDS memory," Dodd said. "A bit got flipped or corrupted. But without the telemetry, we can't see where that FDS memory corruption is."
[...] "We have sheets and sheets of schematics that are paper, that are all yellowed on the corners, and all signed in 1974," Dodd said. "They're pinned up on the walls and people are looking at them. That's a whole story in itself, just how to get to the information you need to be able to talk about the commanding decisions or what the problem might be." [...] "It is difficult to command Voyager," Dodd said. "We don't have any type of simulator for this. We don't have any hardware simulator. We don't have any software simulator... There's no simulator with the FDS, no hardware where we can try it on the ground first before we send it. So that makes people more cautious, and it's a balance between getting commanding right and taking risks."
[...] The spacecraft's vast distance and position in the southern sky require NASA to use the largest 230-foot (70-meter) antenna at a Deep Space Network tracking site in Australia, one of the network's most in-demand antennas.
"The data rates are very low, and this anomaly causes us not to have any telemetry," Dodd said. "We're kind of shooting in the blind a little bit because we don't know what the status of the spacecraft is completely."
Previously on SoylentNews:
Engineers Work to Fix Voyager 1 Computer - 20231215